Evidence Against Salt Keeps Piling Up

When your board-certified cardiologists in Jupiter, Florida, here at The Medical Group of South Florida, talk to our patients about reducing their salt intake, we often get push-back along the lines of, “But doctor, our bodies need salt.”

That’s actually true. A lack of sufficient salt can be dangerous. The body needs salt to function. This necessary mineral helps regulate blood pressure, as well as nerve and muscle function. Iodized salt helps prevent hypothyroidism. Salt, comprising sodium and chloride, helps maintain fluid balance. It helps your body absorb chloride, amino acids, glucose, and water through the intestines. Some studies have even suggested that salt intake which is too low can increase blood pressure, thus leading to cardiovascular disease.

But in general, Americans take in much more salt than they need, not only when adding it while cooking, but in the many processed foods and snacks they consume. And despite claims to the contrary, research shows that reducing salt intake does indeed help to lower blood pressure, often significantly.

Take for example the most recent study on the subject, reported last month in the Journal of the American College of Cardiology. It showed that reducing sodium intake seems to improve blood pressure as well as or better than many drugs. Researchers reexamined data from an earlier study which included 412 middle-aged adults whose blood pressure readings indicated they were pre-hypertensive; that is, their systolic and diastolic blood pressures were considered to be high-normal. None of the participants was on blood pressure medication.

Participants were divided into two groups, one told to eat a normal American high-salt diet, the other instructed to follow a low-sodium diet. The results were clear: Those who restricted their salt intake to below recommended levels saw their blood pressure drop. And those who had the highest blood pressure on entering the study saw the most dramatic decrease in blood pressure.

This study, of course, is not definitive, but echoes others showing that even modest reductions in salt intake can positively impact blood pressure. A 2013 study reported in BMJ (formerly the British Medical Journal) for example, had similar results, with significant decreases in blood pressure as quickly as 24 hours after a drop in sodium intake. Researchers suggested that larger reductions in salt intake would lead to even larger drops in systolic blood pressure.

So, is salt good or bad for you? The answer is, both. As we’ve noted above, the body needs a certain amount of salt to function. That amount is in the neighborhood of 180-500 milligrams a day, far less than the 1,500 to 2,300 milligrams the American Heart Association recommends as optimal daily intake, and the 3,400 milligrams the average American consumes.

Too much salt increases excess fluid in your body, which increases the pressure of blood flowing through your veins. At the same time, it can cause the hormonal system to narrow your arteries. These two factors lead to high blood pressure. Approximately a third of American adults have high blood pressure, and only about half of those have it under control.

So yes, you need some salt. You don’t need much salt, especially if you have—or are at risk for—high blood pressure and cardiovascular disease. If you’re in doubt, please talk with our cardiologists. We can help you sort through the confusion, and recommend the ideal salt intake for your specific medical situation.